Recently, an enlargement of a market of flat-screen devices typified by a liquid display augments a demand for the transparent conductive film. Additionally, the transparent conductive film is employed for an electrode. Further, it is employed for a member constituting a resistive touch panel. Further, it is employed for an electromagnetic wave shielding film. It is employed for various fields besides them. The transparent conductive film of this type, as a rule, is made of metal oxide such as Indium thin oxide (ITO). And, this transparent conductive film is produced with a dry plating method such as sputtering. Thus, the film-forming with these methods necessitates a high temperature. For this, the use of a resin substrate having a poor heat-resistance is greatly restricted. In addition, the film-forming requires a vacuum environment. For this, a gigantic film-forming device is necessitated as the substrate become big. Thus, the film-forming becomes costly. Further, In etc. is hard to obtain because it is rare. For this, it is costly.
The alternative technology, which replaces ITO, has been proposed from such a background. In particular, a wet coating, i.e. a coating technology has been proposed. Among them, attention to a coated film of a carbon nanotube is paid (Non-patent document 1).
However, a big point at issue that when the transparent conductive film employing the carbon nanotube is left as it is for a long time at a high temperature, conductivity thereof declines has been recognized.
As method for solving this point at issue, that is, a method for improving high-temperature durability, the method has been proposed of forming a protective layer upon the conductive film that is comprised of the carbon nanotube (Patent documents 1 and 2).
For example, in the Patent document 1, it has been proposed to form the protective layer such as polycarbonate, polyamide, polyethylene terephthalate, and acrylic resin.
For example, in the Patent document 2, it has been proposed to form the protective layer of the member selected from a group consisting of polyethylene, polypropylene, polyvinyl chloride, styrene resin, polyurethane, polyimide, polycarbonate, polyethylene terephthalate, cellulose, gelatin, chitin, polypeptide, polysaccharides, polynucleotide, and a mixture thereof.
Patent document 1: JP-2004-202948A
Patent document 2: JP-2005-255985A
Non-patent document 1: Applied Surface Science 252 (2005) 425-429